Plaster calculator
How much plaster do I need?
Estimate bags of plaster needed for walls and ceilings based on wall area and number of coats.
Plaster calculator
Plaster calculator result
Plaster types
- Venetian plaster: Decorative finish, requires 2-3 coats
- Lime plaster: Traditional breathable plaster for older buildings
- Gypsum plaster: Modern interior plaster, sets quickly
- Cement plaster (stucco): Exterior application, 3-coat process
Worked example
For example, for a 320 sq ft wall area, applying 2 coats:
- Total area to plaster = 320 × 2 = 640 sq ft
- A 50-lb bag covers roughly 50 sq ft per coat
- Bags needed = 640 ÷ 50 = 12.8 → 13 bags per coat
- For 2 coats: 26 bags total
- Buy a few extra bags for mixing adjustments and repairs
Common mistakes
| Mistake | Why it matters |
|---|---|
| Applying plaster too thick | Each coat should be about ⅛ inch — thick coats crack as they dry |
| Not dampening the surface first | Dry surfaces suck moisture out of plaster too fast, causing cracking and poor adhesion |
| Skipping the scratch coat on lath | Plaster over metal lath needs a rough scratch coat for the brown coat to bond |